Right lads what do i need as far as components and what order or even better if someone can do me some schematic diagram to reduce 12v DC to 0.5V DC no more than 1A draw what i have got to do is replicate the steady output from a post cat O2 sensor voltage and i'm told that around 0.5v is good.

How do i go about making a regulator if i tap of a 12v feed i.e the heater wires to the O2 sensor?

Sure Jonathan or Irvin might be able to shine some light on this on..